Our work is concerned with the genetic organization of the ubiquitous microtubule proteins, alpha- and beta-tubulin, that are implicated in many basic cellular functions such as mobility, cell shape, and cell division. We have recently reported the successful isolation of cDNA clones containing sequences for chicken alpha- and beta-tubulin and gamma- and beta-cytoplasmic actin. The tubulin clones are currently being used to screen a human genomic library so as to isolate the corresponding human tubulin genes. These sequences will be analyzed with respect to their structure, intervening sequences and relationship to one another. Analogous experiments are also being carried out with cDNA clones that code for bovine rhodopsin, an embedded membrane protein that functions as the primary photoreceptor in all vertebrates.